Established in Nairobi in 2004, this is the internationally recognised authority in Somalia. The warlord Abullahi Yusuf was elected as president by MPs, but failed to win support on the ground. In 2006, when an alliance of sharia courts, the Islamic Courts Union (ICU), wrested power from warlords who controlled much of south and central Somalia, the government was saved by invading troops from Ethiopia. Yusuf resigned in 2008 and was replaced by Sheikh Sharif Sheikh Ahmed after the Ethiopians withdrew in January. A moderate Islamist who co-led the ICU, Ahmed supported the ­installation of sharia. His ­government exercises very little authority.

Al-ShabaabCreated from the remnants of the ICU's radical wing, the Shabaab led the initial insurgency against Ethiopian troops, the ­transitional federal ­government and later peacekeepers from the African Union. Commanded by trained ­guerrillas, they are alleged to have links to al-Qaida and are designated as a terrorist organisation by the US. They have carried out numerous suicide bombings, a tactic previously alien to Somalia, and use improvised explosive devices. In some areas under their control the Shabaab practise harsh Islamic law, with penalties including amputations and death by stoning.

African Union mission to SomaliaThis 4,300-strong ­peacekeeping ­mission, ­established with UN approval, is mandated with ­supporting ­government ­structures, ­including the presidency, the port and the airport in ­Mogadishu, the capital, as well as facilitating ­humanitarian aid. Staffed by Ugandan and ­Burundian troops, it has come under frequent attack from ­insurgents, with at least 23 peacekeepers killed since 2007.